The invention relates to a method for position determination for a motor vehicle.
Known methods for position determination for a motor vehicle often comprise a satellite based determination of a geographical position of the motor vehicle; providing digital road map data, which include at least information about road segments in the surroundings of the geographical position; and determining a road segment, on which the motor vehicle is located with high probability, by matching the geographical position with the digital road map data.
The object of the invention is to provide an improved method for position determination for a motor vehicle.
This and other objects are achieved by a method that is intended for position determination for a motor vehicle and that has the following steps:
(a) satellite based determination of a geographical position of the motor vehicle;
(b) providing digital road map data, which include at least information about road segments in the surroundings of the geographical position;
(c) carrying out a first determining step for determining at least a first road segment, on which the motor vehicle is located with high probability, wherein the first determining step is based on a matching of the geographical position with the digital road map data;
(d) retrieval of traffic lane data, regarding at least the number of traffic lanes for the first road segment, from the road map database;
(e) determining the traffic lane, in which the motor vehicle is currently traveling, by use of at least the traffic lane data; and
(f) carrying out a second determining step for determining a second road segment, on which the motor vehicle is located with high probability, wherein the second determining step is based on a matching of the geographical position with the digital road map data and at least the traffic lane, in which the vehicle is traveling.
Thus, the multi-step method according to the invention also includes the acquired information regarding the traffic lane, in which the vehicle is currently traveling, in the map matching process. In this way better decisions can be made, especially in ambiguous situations. The method allows the position to be determined in a better and more reliable way than the known methods from the prior art. The advantages are especially noticeable at the entrance and exit ramps, in particular at the entrance and exit ramps of highways.
In addition, the acquired information regarding the traffic lane, in which the vehicle is currently traveling, can be used for a lane-specific route guidance and corresponding lane change instructions.
Preferably, the second determining step is based on a matching of the geographical position with the digital road map data; the traffic lane, in which the vehicle is traveling; and at least additional traffic lane information. Therefore, in addition to the traffic lane, in which the vehicle is currently traveling, still more lane information is included in the determining step. In this way the accuracy and the reliability can be enhanced even more. The additional traffic lane information can originate, in particular, directly from the lane data, retrieved from the road map database. However, the additional lane information can also be acquired elsewhere—in particular, camera-based. For example, the additional traffic lane information can include the number of lanes, instructions regarding a user restriction for a specific lane (for example, a bus lane), instructions regarding the usage restriction for a specific lane (corresponding to the widely spread lane markings in the area leading up to the road intersections—for example, “left turn arrow”), instructions regarding a suggested utilization for a specific lane, and/or information regarding a distant destination that can be reached by using a specific lane (corresponding somewhat to lane markings known from many highways, in particular in the area leading up to highway intersections and interchanges—for example, “in the direction of . . . ”). In the case of a camera-based acquisition of additional traffic lane information, the camera-based acquisition can be based, in particular, on the camera-based detection of at least a marking that is actually physically arranged on the respective lane and/or based on the camera-based detection of at least one traffic sign that is allocated to at least the respective lane.
According to a preferred embodiment of the invention, the lane, in which the motor vehicle is currently traveling, is determined in a camera-based manner. Thus, the “on-board” acquired information regarding the lane, in which the motor vehicle is currently traveling, is linked in an especially advantageous way to the lane data, retrieved from the road map database. A camera-based determination is technically feasible, in particular, because of the good optical detectability of lane boundary markings that are physically present typically on the side. In this respect different kinds of such lane markings can be differentiated especially by means of their type and thickness.
According to another preferred embodiment of the invention, a lane model of the first road segment is created on the basis of the lane data for the purpose of the second determining step, and the determination of the lane, in which the motor vehicle is currently traveling, is carried out based on the information of the traffic lane model. The use of such a traffic lane model allows, inter alia, an efficient and consistent processing of a variety of traffic lane data.
Such a traffic lane model can include, in particular, information regarding the number of traffic lanes of the first road segment. This information can relate, in particular, to information regarding the exclusion and inclusion of traffic lanes. In this case the traffic lane model can comprise, on the one hand, information regarding the exclusion and inclusion of traffic lanes within the first road segment and, on the other hand, information regarding the exclusion and inclusion of traffic lanes with respect to at least one adjacent road segment. A traffic lane model that is especially easy to utilize is one that has information regarding the exclusion and inclusion of lanes with respect to a road segment, on which the vehicle has traveled before, in particular on which the vehicle has traveled last.
As an alternative or in addition, the traffic lane model can include information regarding the course and/or the arrangement of the individual traffic lanes on the first road segment.
As another alternative or in addition, the traffic lane model can include information regarding the interconnections between the first road segment and other road segments.
According to a preferred embodiment of the invention, the traffic lane model is virtually “driven through” to some extent as a function of the variation over time of the (geo) position of the motor vehicle that can be detected repeatedly in a preferably continuous or quasi-continuous manner. Hence, an absolute position and lane determination is not newly carried out in each computing step, but rather the last computed position and/or lane information is used at least to some extent, in particular at least for the purposes of a plausibility check. The method executing system, in particular an on-board computer of the motor vehicle “remembers” to some extent the lane, in which the vehicle is currently traveling. Preferably, the resulting “remembered” or rather buffered information about the lane, in which the vehicle is currently traveling, is updated, when changes in the lanes (for example, the inclusion or exclusion of lateral lanes) are recorded in the digital map and/or are contained in the lane model, which is built at least partially from the digital map data.
A traffic lane model, which is enriched with a plurality of data, and optionally the addition of information, acquired on the basis of a sensor, can make it possible to determine in a clear and unambiguous way the position of the motor vehicle and/or the lane, in which the vehicle is traveling, and/or the road segment, on which the vehicle is traveling, by many methods and to some extent in different ways. In such cases it can be advantageous to execute, in addition to a first determination in a first way, a second determination in a second way so as to be checked for plausibility and/or redundancy.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.